InstantFit TLED (instant fitting tubular LED lighting device, throughout this specification, unless the context clearly requires otherwise TLED refers to InstantFit TLED) is a retrofit lighting device for tubular fluorescent lamp (TL) fittings. The TL fitting may be a standard fitting for tubular fluorescent lamps, such as T8/T5/T10 etc. Many common fittings or luminaires for tubular fluorescent lamps comprise a high frequency (HF) ballast, such a ballast is a common component of fittings for tubular fluorescent lamps, as is known to the skilled person. As the HF ballast and TL system is widely used throughout the world, and as TLEDs are increasing used as replacements for tubular fluorescent lamps, InstantFit TLEDs are most easily installed without removing the HF ballasts.
As a result of the inclusion of a HF ballast, the output of the fitting to the lighting device is designed as a constant current source with a high frequency (up to 100 kHz), a change in the load (in this case the TLED) has limited impact on the current output of the ballast. Therefore, if the TLED is not properly connected to the lamp fitting or luminaire, for example, because there is some distance between the lighting device electrical connector and lamp fitting electrical connector, arcing between the electrical connector of the lighting device and the electrical connector of the lamp fitting will result. This arcing and/or intermittent contact at HF may result high temperatures which could melt the lamp holder, possibly overheat the total system, and, in a worst case, cause a safety problem. Therefore, a solution is required to prevent or at least substantially reduce this problem; in particular, it is desired to provide a safer InstantFit TLED.
FIG. 1 shows the total system of a TLED 10 mounted in a lamp fixture or luminaire 20 which includes a HF ballast. The inclusion of a HF ballast is one of the most common configurations for tubular fluorescent lamp fittings. The lamp fixture or luminaire 20 and ballast can be 1/2/3/4 lamp system, in which 1, 2, 3 or 4 TLEDs can be mounted in the luminaire 20.
FIG. 2 shows that if the electrical connectors of the lighting device are not properly connected to lamp holder 22, then a gap A or B may form. Whether the gap is at the end A or B or both depends on the end-user's installation of the TLED 10 in the luminaire 20. In the situation such as that illustrated in FIG. 2, the gap between the TLED and lamp holder can cause arcing as a result of the inclusion of a ballast in the luminaire 20. As the HF ballast operates as a HF constant current source, gaps A and/or B can result in intermittent contact and result in high impedance. Accordingly, the HF constant current source can cause arcing across the gaps A and/or B; in turn this can result in a high temperature. If the lighting device and ballast are not shut down quickly enough, the arcing may overheat the components of the luminaire and/or lighting device, including the lamp holder and/or the fixture, this can create a safety hazard.
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